Modulator



April 21, 1959 H. T. MORTIMER 2,883,605

MoDULAToR Filed Marsh 27', 1957 2 meets-sheet z INVENTOR HARRY T.MORTIMER Annnnnnnnnnn ATTORNEY5 United States Patent O MODULATR Harry T.Mortimer, Anaheim, Calif. Application March 27, 1957, Serial No. 648,982

8 Claims. (Cl. 321-68) (Granted under Title 35, U.S. Code (1952), sec.266) whichlare magnetically coupled with each other; the firstcore hasan input Winding disposed thereon for receiving an alternating signalwhile the second core has an output'winding and aV biasing windingdisposed thereon. A unidirectional current is applied to the biasingwindingy for producing a longitudinal flux in the second coresubstantially parallel to the direction of grain orientation while analternating signal is applied to the input windingv disposed on theother core. The time varying magnetic flux produced in the first core bythe alternating signal induces a voltage in the second core. The secondcore is constructed of magnetic material which is a good con-v ductor sothat the induced voltage causes a current to flow around the corelongitudinally along essentially the same path as the unidirectionalflux created by the' biasing current. second core which is substantiallyperpendicular to the longitudinal flux and to the direction of grainorientation. The transverse flux causes the component of thelongitudinal flux which is perpendicular to the output winding to varyat twice the frequency of the alternating signal applied to the firstcore, and hence an output voltage is induced in the output winding whichhas a frequency twice that of the alternating signal. The magnitude ofthe output voltage can be controlled by the amount of biasing currentapplied to the second core, and the phase of the output voltage dependson the polarity of the lbiasing current.

The invention is capable of amplifying the direct current applied to thebiasing winding and the amplified signal which is of an alternatingcurrent nature can be furtheramplified without the difliculties inherentin the amplification of direct current signals. Further the apparatus ofthe invention has a fast response time limited only by the speed ofmagnetization of the core for a given signal, is more eicient and cancarry a heavier load than conventional second harmonc modulators.

An object of the present invention is the provision of a magnetic secondharmonc modulator.

Another object is vto provide a fast response second harmonc modulatorutilizing grain oriented magnetic materials.

A further object of the invention is the provision of a fast responsesecond harmonc modulator utilizing grain oriented magnetic materials inwhich the output voltage is directly Proportional to a direct currentbiasing signal applied to the device.

Still another object is to provide a magnetic second harmonc modulatorwhich has a fast response time, is

eflicient and is capable of carrying a heavy load.

This current sets up a transverse flux in the= Other objects and many ofthe attendant advantages of this invention will be readily appreciatedas the same becomes better understood by reference to the followingdetailed description When considered in connection with the accompanyingdrawings in Which like reference numerals designate like partsthroughout the figures thereof and wherein:

Fig. 1 shows a schematic representation of a typical embodiment of themagnetic second harmonc modulator of the present invention;

Fig. 2 discloses another embodiment of the invention in which an E coreis used to produce flux ynecessary to induce a voltage in the toroidalcore; and

Figs. 3 and 4 show vector diagrams of the flux and the magnetic fieldspresent in the grain oriented core of the present invention.

Referring'now to the drawings, in which like reference charactersdesignate like or corresponding parts throughout the second views, thereis shown in Fig. 1 (Which illustrates one embodiment) a magnetic core 11having a Winding 12 disposed thereon for the reception of an alternatingsignal supplied from signal source 13. Magnetically linked with the core11 is another magnetic core 14 constmcted of a grain Oriented magnetcmaterial such as Hypersil in which the direction of grain orientation istangent to the curve of the core 14 at every point in the core. Core 14could, for example, be wound from thin Hypersil tape in which thedirection of grain orientation is parallel to the longitudinal directionof the tape. Although core 14 is preferably of grain oriented material,core 11 need not be of such material.

A control or biasing winding 15 is disposed upon the core 14, and aVariable unidirectional current source comprising, for example, abattery 16 and a Variable resistor 17 is connected thcreto for producinga magnetomotive force in the winding 15 which produces a longitudinalflux in the core 14 in the direction of the grain orientation of themagnetic material. An inductor 18 and a capacitor 19 is provided topresent a high impedance to second and higher harmonics of thealternating signal from source 13 in order to isolate the unidirectionalcurrent source from such harmonics.

An output winding 21 disposed on the core 14 has a load circuit 22connected thereto and a voltage varying at twice the frequency of thesignal -from source 13 Will be induced therein and delivered to the load22.

A theory of operation of the device is as follows, however, it is notintended that the invention in any way be restricted by thisexplanation. The unidirectional current from the battery 16 creates anon-varying longitudinal flux in the core 14 in the direction of thegrain orientation of the magnetic material. Since this flux isnon-varying, that is, there is no change in the flux linking the outputwinding 21 with respect to time, no voltage will be induced therein andno output will result. When an alternating current is applied to thewinding 12 from the source 13 a time varying magnetic field is set up inand around the core 11. The core 14 cuts this time varying field in thesame manner as a winding in a transformer and a voltage is inducedtherein which causes current to flow around the core 14 along the sameaXis as the non-varying longitudinal flux and the grain orientation.Since a current creates a magnetic field perpendicular to its direction,a transverse magnetic flux is set up in the core which is perpendicularto the constant flux produced by the winding 15. This transverse fieldvaries at the same frequency as the signal from the source 13, but ascan be appreciated by reference to Fig. 1, this flux is parallel to theturns of the winding 21 and hence no voltage is induced because of thisfield acting alone. However, this transverse field 'causes thec omponentof the effective longitudinal flux,

assaeos whichl links with the output winding 21 to vary at twice thefrequency of the alternating signal from the source 13.

Referring now to Pigs. 3 and 4, there is shown a vector representationof the magnetic forces acting on the core 14 as well as the longitudinalflux set up in the core. The vector HL represents the magnetic fieldintensity created by a current flowing in the winding 15, and it isassumed that HL is positive, as shown in Pig. 3, when the battery has apolarity as shown in Pig. 1. This magnetic field HL creates alongitudinal flux qbL in the direction of grain orientation of themagnetic material in core 14. The alternating current produced by theinduced voltage in the core 14 creates a transverse field of intensitydesignated by HT which acts to rotate the flux vector (pr, so that itlines up with the resultant magnetic field designated by resultant H.The flux magnitude qbL will remain essentially constant and hence theflux linking the winding 21 will be bL cos and the change in flux isrepresented by -dom and a negative voltage will be induced in the outputwinding 21. When the alternating current in the core goes through zerothe vector 42:, will return to its original position, a change of flux-l-doL will link the output winding 21 and a positive voltage will beinduced therein. Tracing this action through a complete current cycle,the vector oh will be in line with HL and there will be no fieldcornponent HT when the current has zero value. As the current goespositive -t-I-IT will increase and the vector cpi, will be rotatedclockwise until HT and qL have reached the position shown in Pig. 3 whenthe current has reached a maximum value. The reduction in flux linkingthe winding 21, -d4 L will cause a negative voltage to be inducedtherein. As the current again returns to a zero value HT reduces tozero, pL returns to its original position and a positive voltage isinduced in the output winding because of an increase of flux -l-dtp-Llinking the output Winding. As the current goes negative a negativetransverse magnetic field designated by -HT is created in the core whichrotates the vector bL in a counterclockwise direction until it reachesthe position shown in Pig. 3 and a change of flux designated by -d pL islinked with the output winding 21 inducing a negative voltage therein.When the current returns to zero, -HT is reduced to zero, the vector pl,is aligned with HL, and a change in fiux +d pL links the winding 21inducing a positive voltage therein.

Thus the output voltage induced in the winding 21 varies at twice thefrequency of the current in the core 14 Which alternates at a frequencyequal to that of the signal from the source 13. If the battery 15 shownin Pig. l is reversed, the magnetic field in the core 14 will benegative as shown in Pig. 5, that is, a magnetic field -I-lL and amagnetic flux -4 L will exist in the core. When the current produced bythe induced voltage goes positive the vector -qsL is rotatedcounterclockwise by the magnetic field -l-HT, the flux which links withthe output winding 21 is increased by an amount -I-doL and a positivevoltage is induced in the winding. When the current comes back to zerothe flux changes by an amount -doL inducing a negative voltage in theoutput winding. Similarly, when the current goes negative first apositive and then a negative voltage is induced in the output winding.Thus it is manifest that the phase of the output voltage is shiftedthrough 180 when the flux qbL is changed from positive to negative by achange in the polarity of the unidirectional current source 16.

lt can also be readily deduced from an inspection of Pigs. 3 and 4 thatthe magnitude of the output voltage induced in the winding 21 isdependent o-n the magnitude of the longitudinal flux qsL as this voltageis proportional to and dqL is qL-oL cos 6. Thus if the frequency and thepeak value of the magnitude of the signal from signal source 13 ismaintained constant, the maximum value of HT and -HT will remainunchanged and the time required for the vector oL to be rotated to theposition indicated in Pigs. 4 and 5 and return to its normal positionwill remain constant, thus the value of the induced voltage in theoutput winding will be directly proportional to the magnitude of theflux qbL.

Pig. 2 illustrates an embodiment of the invention in which a threelegged magnetic core 23 is used in lieu of the core 11 in Pig. 1. Inthis case the signal source 13 supplies an alternating signal to thewinding 12 which in turn creates a time varying flux in the middle legof the core. The core 14 is placed around this middle leg and the timevarying magnetic field induces a voltage in the core which causes a timevarying current to flow circumferentially thus producing the timevarying transverse field in the core 14. The functioning of the deviceis the same as that of the embodiment illustrated in Pig.v 1.

Westinghouse Type C Hypersil cores can be conveniently used to constructthe embodiment shown in Pig.w 1. These C-shaped cores are constructed oflaminated grain Oriented material and are designed to be pressedtogether by a banding strap after the windings have been positionedthereon. Alternatively the core 14 having windings 15 and 21 positionedthereon can be constructed of continuously wound grain Oriented magnetictape and it has been found that this is frequently preferable inorder toreduce the number of ampere turns necessary to control the flux in thecore.

Thus the present invention provides a magnetic second harmonic modulatorwhich utilizes certain Characteristics of grain Oriented material andwhich has a fast response time, is efiicient and is capable of carryinga heavy load.

It should be understood, of course, that the foregoing disclosurerelates to only preferred embodiments of the invention and that it isintended to cover all changes and modifications of the examples of theinvention herein chosen for the purposes of the disclosure, which do notconstitute departures from the spirit and scope of the invention.

What is claimed is:

1. A second harmonic modulator comprising a core of grain Orientedmagnetic material, means for producing a unidirectional magnetic flux insaid core in the direction of grain orientation, means for producing atime varying magnetic field in said core in a direction perpendicular tothe direction of grain orientation, and a frequency selective outputmeans magnetically coupled to said core tuned to twice the frequency ofsaid time varying magnetic field.

2. A second harmonic modulator comprising a core of grain Orientedmagnetic material, a control winding disposed upon said core, meansapplying a unidirectional current to said control winding for producinga unidirectional flux in said core inthe direction of grain orientation,means for producing a time varying magnetic field in said coreperpendicular to the direction of grain orientation and a frequencyselective output means magnetically coupled to said core tuned to twicethe frequency of said time varying magnetic field.

3. A second harmonic modulator comprising a first core of grain Orientedconductive magnetic material,

means for producing a unidirectional magnetic flux iny said core in thedirection of grain orientation, means adjacent said first core forinducing alternating current to flow in said first core in the directionof grain orientation, said alternating current producing a time varying4. A second harmonic modulator comprising a first core of grain orientedmagnetic material, means for producing a unidirectional magnetic flux insaid core in the direction of grain orientation, a second magnetic coremagnetically coupled to said first core, means for producing a timevarying magnetic field in and around said second core oriented andintersecting said first core in a direction perpendicular to thedirection of grain orientation and a frequency selective loadmagnetically coupled to said first core tuned to twice the frequency ofsaid time varying magnetic field.

5. A second harmonic modulator comprising, a first toroidal core ofgrain oriented magnetic material, the grain being oriented in acircumferential direction, means for producing a steady unidirectionalflux in said core in the direction of the grain orientation, a secondtoroidal core, means for producing a time varying flux in said secondcore in a circumferential direction, said second core being interlinkedwith said first core with a portion of said second core locatedsubstantially at the center of said first core, and a frequencyselective output means magnetically coupled to said first core and tunedto a frequency harmonically related to the frequency of said timevarying flux.

6. A second harmonic modulator comprising, at least first and secondseparate interlinked continuous paths of magnetic material having apermeability greater than air, means adjacent said first path forproducing a varying strength magnetic flux in said first path along thelength thereof, means adjacent said second path for producing a steadystrength unidirectional magnetic flux along the length thereof, outputmeans magnetically coupled to the flux of said second path forextracting energy from said unidirectional flux When said unidirectionalfluX is varied, said second path consisting of grain oriented materialWith the grain oriented along the length of said second path.

7. The modulator according to claim 6 Wherein the grain orientedmaterial is electrically conductive.

8. The modulator according to claim 6 Wherein at least one additionalpath of magnetic material having a permeability greater than air isconnected in parallel With a portion of said first path to form a thirdcontinuous path interlinked With said second path.

References Cited in the file of this patent UNITED STATES PATENTS2,445,s57 Mccreary July 27, 1948 2,46l,992 McCreary Feb. 15, 1949FOREIGN PATENTS 886,159 Germany Aug. 10, 1953

